Not applicable.
Not applicable.
1. Field of the Invention
The present invention is related to retrieving packers and their extensions from wellbores and, in particular, milling a packer with a packer retriever engaged to the packer or its extension without requiring rotation of a grapple of the packer retriever.
2. Description of the Related Art
To retrieve a packer, prior packer retrievers have to exit the inside of the packer. These packer retrievers cannot engage the smooth bore of the packer and allow for rotation while milling, but must completely exit the packer. Rotation is necessary because the packer retriever is tied directly or constructed to turn with the milling tool, and rotates underneath it.
Slips on the outer edge of the packer hold the packer in place. Typically, the outer part of the packer and slips (e.g., the outer xc2xd-inch) are milled away using a hollow-type or xe2x80x9cwashpipexe2x80x9d milling tool, allowing the packer to become loose for retrieval. Other types of milling tools, such as a solid milling tool without a bore (i.e., without an inside diameter or I.D.), also can be used. These tools are used to mill the packer until it breaks loose. More information on packer retrievers can be found in Instruction Manual No. 5/2710, entitled xe2x80x9cBowen Simplex Packer Retrievers,xe2x80x9d by Bowen Tools Division of IRI International Corporation (National Oilwell), September 1991, which is incorporated by reference herein in its entirety.
Today, because smooth bore extensions (e.g., tubing or pipe) often hang off the bottom of the packer, an even longer tool holding a packer retriever would be required to retrieve the packer and the extension. For example, a 30 foot piece of tubing hanging off the bottom of the packer might require a 35 foot extension on the milling tool to enable the packer retriever to exit the lower end of the tubing. This is because milling can proceed only if the packer retriever completely exits the tubing, as indicated above, and rotates along with the milling tool. Therefore, there is a need to engage a smooth I.D. of a packer or its extension without having to exit the packer or the extension to reach open hole below.
One type of device, the so-called xe2x80x9cITCOxe2x80x9d-type releasing spear, can be used to engage a smooth I.D. of a packer or its extension. Once it has passed through the packer, however, this releasing spear is forced to rotate freely with the hollow I.D. milling tool, as described above, to which it is attached directly. If the milling tool rotates at 60 turns per minute, then the releasing spear also turns at that same rate and does not wear on anything. If the rotating releasing spear instead were engaged to the smooth I.D. of the packer or its extension to be retrieved, then material would wear and burn from the contact as the spear rotated. The releasing spear would not last if 6 to 8 hours were required to mill the packer. This would happen if the spear were not allowed to remain stationary during milling. More information on ITCO-type releasing spears can be found in Instruction Manual No. 5/2300, entitled xe2x80x9cITCO Type Bowen Releasing Spears,xe2x80x9d by Bowen Tools, Inc., June 1994, which also is incorporated by reference herein in its entirety.
Because of such problems, the typical spear is attached to a milling tool having a slip mechanism provided. A bearing typically is used on the inside of the milling tool as the slip mechanism. The slip mechanism requires use of the hollow-type milling tool, for example, as shown on page 5 in the aforementioned instruction manual entitled xe2x80x9cBowen Simplex Packer Retrievers.xe2x80x9d If, however, the packer retriever could exit the I.D. of the packer or its extension, then either a solid or a hollow milling tool can be used. History has shown that hollow milling tools sometimes do not perform properly. For example, the milling tool and packer may have to be jarred or otherwise manipulated to remove it from the hole. This may be because a slab of material remains after partial milling on the outer one-half inch of the packer or something in the packer has become loose, creating drag or an immovable obstacle. Typically, success can be achieved better with a solid milling tool, which is flat on the bottom with perhaps just enough room for a shaft to come out to hold onto the tool. But, assuming open hole cannot be reached and a smooth I.D. must be engaged, then something must remain stationary, usually the spear, while the milling tool turns.
To resolve or reduce the effects of the above or other problems, a packer retriever is needed that can run with a solid milling tool and engage the smooth I.D. of the packer or its extension to be retrieved. Such a tool would not use the standard slip mechanism or have the spear remain stationary while remaining engaged on the smooth I.D of the packer or its extension. The tool must remain in the engaged position during operation.
Embodiments of the invention feature a packer retriever that can engage a packer or its extension having a substantially smooth inside diameter for retrieval from a wellbore. The packer retriever includes a grapple, grapple carrier, and a mandrel. The grapple and the grapple carrier form a grapple body. The grapple body is rotatably coupled to the mandrel, which is inserted through the grapple body and is attached directly to a milling tool. The grapple body is inserted in or through a bore of the packer to engage the packer or an extension thereof before the packer is milled. The packer retriever allows the mandrel to rotate constantly while the grapple body remains stationary during milling. The packer retriever can remain in the engaged position to prevent the packer from falling if the packer breaks loose from milling. The packer retriever can transfer torque to the packer, if desired or required, and can also be engaged and disengaged or released multiple times.
Embodiments of the invention feature a releasing mechanism in which torque is transferred to a packer retriever such that a compressive force is applied to a portion of the packer retriever, making it easier to release the packer retriever from the packer or its extension.
Embodiments of the invention feature a packer retriever having a grapple body that does not rotate when released below from teeth on a nut of a mandrel on which the grapple body is rotatably coupled. The grapple body does not rotate during a milling procedure on a packer, but with the nut engaged to the grapple carrier, the grapple body does rotate while releasing from the packer by effectively unscrewing from the packer I.D. These embodiments include a shoulder and bearing on the grapple body that allow the mandrel, but not the grapple body, to rotate while reducing the effects of wear.
Embodiments of the invention feature a packer retriever adapted for use with a milling tool in a wellbore. The packer retriever includes a grapple body having a central opening and external teeth (wickers) on a grapple for engaging inside a bore of a packer. The packer retriever also includes a mandrel having a shaft coupled directly (e.g., screwed) to the bottom of the milling tool. Alternatively, a stinger, which is a separate part or extension (i.e., of the shaft) can be installed between the milling tool and the packer retriever to regulate the distance of the tool below the milling tool. The shaft typically has a smooth external surface adapted to extend through the central opening to permit rotation and/or vertical movement of the shaft relative to the grapple body while the external teeth of the grapple are engaged inside a bore of a packer. In these embodiments, the grapple teeth have an external diameter sized for entry into and positioning in the bore of the packer or its extension, if any, upon application of a downward force on the grapple body for catching the packer to prevent it from falling while the packer is milled.